Three Important Network Switching Parameters You Must Consider

Fiber optic network switches are a valuable asset to any high performance surveillance networks. They are analyzed on the basis of several performance factors including switching capacity, forwarding rate, switching bandwidth and more. The switches may not perform as expected if there is any mismatch of parameters. Although each of these terms may appear understandable, they wield a great importance during your selection. What do each of these parameters mean? Read this post to know answers for the same.
 

Important Network Switching Parameters Analyzed

Forwarding rate or forwarding performance, switching bandwidth, and network speeds are important parameters used to measure the performance of fiber optic network switches. The following pointers will help you understand these parameters and their calculation.

• Switching Capacity:

  It is also referred to as backplane width and it refers to the maximum value of data, which can be transmitted between a data bus or interface card. This is indicated in bps.
  The switching capacity of a fiber optic network switch = total number of ports * rate of the port * 2 (for full-duplex). The switching capacity of the 24-port 100 M switch will be 24*100*2 and this value comes to 4.8Gbps.

• Forwarding Performance:

  This is also referred to as forwarding rate in technical terms. This indicates the packet forwarding capabilities of the fiber optic switches. It is measured in packet per second or PPS. It shows the number of data packets forwarded by the switch in a second. In Ethernet switches, the frame size of data is limited during the transmission due to the presence of Ethernet conflict detection mechanism. The Ethernet transmits minimum data frame of 84 bytes. It is calculated as minimum data frame rate + preamble bytes + interframe gap. Here, the minimum data frame rate is 64byte+ 8byte preamble bytes+ 12 bytes interframe gap.
  For example, consider a 100 Mbit/seconds Ethernet interface. It has an Ethernet interface rate of 12.5 Mbyte/s. How is this calculated?
  1 byte = 8 bits, Ethernet Interface Rate = 100/8 or 12.5 Mbyte/seconds. It means a 100 Mbit/seconds Ethernet interface can deliver 12.5M bytes or 12500000byte per second. If we assume that all data frames transmitted are of 84byte size then the data frame forwarded by the Ethernet port of 100 Mbit/seconds is 12500000/84=148809pps (frame/second) =0.1488Mpps = 148.8kpps
  
  It can be rightly said that a 100 Mbit/seconds Ethernet interface has a packet forwarding rate of 0.1488Mpps. The Gigabit Ethernet interface has a packet forwarding rate of 1.488 Mpps, and 10G Ethernet interface has the packet forwarding rate of 14.88 Mpps.
  
  Forwarding Rate = Port Numbers x Port Speed/1000 x 1.488 Mpps. It can be simply put as 8*100/1000*1.488Mpps = 1.2Mpps. If the forwarding rate of the switch is less than this, then it may face a delay. This delay may further intensify if there is high capacity data for receive and send.

• Switching Bandwidth and Forwarding Bandwidth:

  Here, the switching bandwidth refers to the total amount of data, which can be transmitted through the switching plane. Forwarding bandwidth refers to the amount of data that can be forwarded to the interfaces. The calculation of these will be based on the optimal conditions.